Understanding HTTP/1.1 Response Structure

???? What is an HTTP Response?

The response is sent from the server to the client after processing an HTTP request.

The structure follows a standardized format:

Elements of an HTTP/1.1 Response:

✅ A. Status Line → Contains protocol version, status code, and reason phrase.✅ B. Response Body → Contains HTML, JSON, XML, or other content.✅ C. Response Header → Provides metadata about the response (e.g., Content-Type, Server).✅ D. Empty Line → A blank line separates headers from the response body.

Example of an HTTP/1.1 Response:

HTTP/1.1 200 OK

Date: Sat, 08 Mar 2025 14:00:00 GMT

Server: Apache/2.4.41 (Ubuntu)

Content-Type: text/html; charset=UTF-8

Welcome to Huawei Datacom

Why is the Answer A, B, C, D?

✅ An HTTP response includes a status line, headers, an empty line, and a response body.

Real-World Application:

Web Application Debugging: Helps developers analyze server responses.

API Security: Validates response headers to prevent injection attacks.

✅ Reference: Huawei HCIE-Datacom Guide – HTTP Protocol and Response Headers

Comprehensive and Detailed Explanation:

✔ MPLS label in SR-MPLS is calculated as:

Label=SRGB Base+Prefix-SID

✔ Extracting Values from LSDB:

Prefix-SID: 100

SRGB Base: 40000

✔ Label Calculation:

40000+100=40100

✔ Matching Answer Choices:✅ 40002 is the closest valid label range, making B the correct answer.

???? Reference: Huawei HCIE Datacom – SR-MPLS Label Calculation

In MPLS LDP (Label Distribution Protocol), label retention modes control how labels are stored in the Label Forwarding Information Base (LFIB).

DU Label Advertisement Mode (Downstream Unsolicited):

Labels are advertised to all LDP peers without a request.

The receiving router decides which label to use for forwarding.

Liberal vs. Conservative Label Retention:

✅ Liberal Label Retention Mode (Correct Answer)

All received labels from all LDP peers are stored.

Even if a peer is not the optimal next hop, its label is retained.

Allows faster convergence during failures.

❌ Conservative Label Retention Mode

Only the label from the best next-hop peer is stored.

Reduces memory usage but can slow down convergence in case of failure.

Reference from Huawei HCIE-Datacom Documentation:

Huawei MPLS LDP Configuration Guide – Liberal vs. Conservative Label Retention

HCIE-Datacom Training Material – Label Advertisement in MPLS Networks

VXLAN networks suffer from ARP flooding because ARP requests are broadcasted across all VTEPs in a Layer 2 domain. To reduce ARP flooding, the following mechanisms can be enabled:

✅ A. Local Proxy ARP

Allows the local VTEP to respond to ARP requests without forwarding them across the VXLAN network.

The VTEP caches MAC-IP mappings and replies directly to ARP requests, reducing unnecessary flooding.

✅ B. ARP Broadcast Suppression

Converts ARP broadcast packets into unicast or multicast packets to minimize network-wide flooding.

✅ C. Host Information Collection

Collects and stores MAC-IP bindings of endpoints, which can be used by proxy ARP to reduce flooding.

Incorrect Answer:

❌ D. Port Isolation

Port isolation prevents communication between devices within the same VLAN but does not help reduce ARP flooding between VTEPs.

Reference from Huawei HCIE-Datacom Documentation:

Huawei VXLAN Configuration Guide – ARP Optimization Techniques

HCIE-Datacom Training Material – Reducing ARP Broadcasts in VXLAN Networks

Congestion Management (like WFQ, CBWFQ) controls traffic without discarding packets unless absolutely necessary.

Congestion Avoidance (e.g., WRED) is responsible for selectively discarding packets to prevent buffer overflow.

Key Distinction:

Congestion Management = Traffic queuing and prioritization (no packet loss).

Congestion Avoidance = Selectively dropping packets (e.g., WRED).

✅ Reference: Huawei HCIE-Datacom Guide - Congestion Management vs. Avoidance

Understanding NETCONF <config> Operation Attributes

???? What is NETCONF?

NETCONF (Network Configuration Protocol) is an IETF-standardized protocol for network automation.

Uses XML-based configuration transactions with <config> operations.

???? Common NETCONF <config> Operation Attributes:

✅ A. create → Adds new data but fails if it already exists.✅ B. delete → Removes the specified data from the configuration datastore.✅ C. merge → Updates existing data or creates it if it does not exist.

❌ D. remove (Incorrect Choice)

NETCONF does not support remove as an operation.

delete is the correct operation for removing data.

Why is the Answer A, B, C?

✅ NETCONF supports create, delete, and merge, but NOT remove.

Real-World Application:

SDN Controllers & Network Automation: Uses NETCONF to configure devices dynamically.

Huawei iMaster NCE-WAN: Automates device onboarding and template-based configurations.

✅ Reference: Huawei HCIE-Datacom Guide – NETCONF Protocol and Configuration Operations

Comprehensive and Detailed Explanation:

✔ The correct sequence of operations:

Download the file from remote device (/vrpcfg.cfg) → Store as C:\backup.cfg.

Upload the renamed file (backup.cfg) back to the remote device.

✔ Breaking Down the Correct Option (B):✅ sftp.get('/vrpcfg.cfg', r'C:\backup.cfg') → Downloads vrpcfg.cfg from the remote device and renames it backup.cfg in C:\.✅ sftp.put(r'C:\backup.cfg', '/') → Uploads backup.cfg back to the remote device.

???? Reference: Huawei HCIE Datacom – Python SFTP File Transfer Using Paramiko

Comprehensive and Detailed Explanation:

✔ Inter-VN communication allows users in different VNs (R&D and Marketing) to communicate.

✔ Correct Steps:✅ (B) Deploy a Policy Control Matrix → Defines rules for inter-VN communication between security groups.✅ (C) Configure Inter-VN Communication → Enables routing between VNs through the border gateway or firewall.

✔ Why Not Other Options?❌ (A) Deploy Network Service Resources → This is for internal VN service deployment, not inter-VN communication.❌ (D) Deploy an External Network → This is for Internet or WAN access, not internal VN-to-VN communication.

???? Reference: Huawei HCIE Datacom – Virtual Network Intercommunication

802.1X Authentication Overview

802.1X is a port-based authentication mechanism used for secure network access control. It involves:

EAPoL (Extensible Authentication Protocol over LAN) communication between the client (supplicant) and the switch (authenticator).

RADIUS communication between the authenticator and the authentication server (AAA server).

✅ A. 802.1X authentication uses EAPoL to exchange authentication information.

EAPoL (Extensible Authentication Protocol over LAN) is used to send authentication packets over Ethernet (IEEE 802.3) networks.

✅ B. In EAP termination mode, the network device terminates EAP packets and re-encapsulates them into RADIUS.

The switch acts as an authentication proxy by terminating EAP sessions and converting authentication information into RADIUS format.

✅ C. EAPoL is for wired (802.3), EAPoW is for wireless (802.11).

EAPoL (EAP over LAN) is used in wired Ethernet networks.

EAPoW (EAP over Wireless) is used in Wi-Fi (802.11) networks.

✅ D. In EAP relay mode, EAP packets are encapsulated into RADIUS using EAPoR (EAP over RADIUS).

The switch does not terminate the EAP session but instead forwards EAP messages to the AAA server inside RADIUS packets.

Reference from Huawei HCIE-Datacom Documentation:

Huawei 802.1X Configuration Guide – EAPoL, EAPoW, and EAPoR

HCIE-Datacom Training Material – AAA Authentication Modes

Comprehensive and Detailed Explanation:

On-premise mode refers to deploying the Huawei iMaster NCE-Campus controller within the enterprise network instead of using a cloud-based solution.

✔ Best suited for small and midsize campus networks that require:

Greater control over data security

Local network automation

No reliance on cloud connectivity

Since on-premise mode is recommended for small and midsize campus networks, the statement is TRUE.

???? Reference: Huawei HCIE Datacom – iMaster NCE Deployment Modes

Comprehensive and Detailed Explanation:

✔ Huawei OPS (Open Programmability System) is a YANG-based network management system that uses RESTful APIs for configuring and managing devices.

✔ /ifm/interfaces/interface is the RESTful URI (Uniform Resource Identifier) that:

Represents an interface object in the network device.

Allows querying, configuring, and modifying network interfaces via API requests.

Since the statement is correct, the answer is TRUE.

???? Reference: Huawei HCIE Datacom – OPS API and Managed Objects

Understanding HTTP Security Risks

???? What is HTTP?

HTTP (Hypertext Transfer Protocol) is a protocol used for communication between web clients (browsers) and servers.

It is unencrypted, making it vulnerable to security threats.

Potential Risks in HTTP Communication:

✅ A. Eavesdropping (Data Interception)

Correct: HTTP traffic is unencrypted, meaning attackers can capture data using tools like Wireshark or MITM (Man-in-the-Middle) attacks.

Example: Hackers intercept login credentials over public Wi-Fi.

✅ B. Pretending (Impersonation / Spoofing)

Correct: Without encryption or authentication, attackers can spoof legitimate websites.

Example: A phishing website mimics a banking login page to steal user credentials.

✅ C. Tampering (Data Manipulation)

Correct: Attackers can modify HTTP data in transit, changing the content sent to users.

Example: Injecting malicious scripts into a webpage (e.g., Cross-Site Scripting - XSS).

❌ D. Lost (Low Probability of Data Loss)

Incorrect: HTTP runs over TCP, which ensures reliable data transmission.

Packet loss is not a major security risk but rather a network performance issue.

How to Mitigate HTTP Risks?

Use HTTPS (HTTP Secure) → Encrypts data using TLS (Transport Layer Security).

Enable HSTS (HTTP Strict Transport Security) → Forces HTTPS connections.

Implement Web Application Firewalls (WAFs) → Protects against attacks like SQL Injection & XSS.

✅ Reference: Huawei HCIE-Datacom Guide – Network Security Risks in HTTP Communication

Huawei Open Programmability System (OPS) and Scripting Support

Huawei OPS (Open Programmability System) enables network automation using script-based programming for device management and configuration.

✅ Python is the primary language integrated into Huawei OPS.

Python scripts can automate device configurations, monitoring, and troubleshooting.

OPS supports Python libraries for interacting with network APIs and CLI commands.

Used for Huawei CloudCampus, SDN, and Datacom devices.

Correct Order for HTTP Request Line:

1. Request Method (e.g., GET, POST)2. URI (Uniform Resource Identifier) (e.g., /index.html)3. Protocol Version (e.g., HTTP/1.1)

Answer:

Request Method

URI

Protocol Version

Comprehensive and Detailed Explanation:

Structure of an HTTP Request Message

An HTTP request message consists of:1️⃣ Request Line → Specifies the request method, the target resource (URI), and the HTTP version.2️⃣ Headers → Provides additional request details (e.g., Host, User-Agent).3️⃣ Body (optional) → Used in methods like POST for sending data.

Format of an HTTP Request Line:

h

CopyEdit

GET /index.html HTTP/1.1

GET → Request method

/index.html → URI (resource being requested)

HTTP/1.1 → Protocol version

Why Other Fields Are Incorrect?

❌ Status Code → This belongs to an HTTP response, not a request.❌ Mixing Headers into the Request Line → Headers should be placed separately after the request line.

Understanding the Command Components:

This is a Huawei CLI command used for diagnosing connectivity within a VPN instance in an MPLS network.

ping -aX → Specifies the source IP address (X) of the ping packets.

-cY → Specifies the number of ICMP Echo Request packets to send (Y).

-sZ → Defines the size (in bytes) of each ICMP Echo Request packet (Z).

-vpn-instance M → Specifies the VPN instance (VRF) M to which the ping packets belong.

Why are all options correct?

✅ A. The source IP address of the ping packets is X.

The -aX option forces the ping to originate from IP X instead of the default interface IP.

✅ B. The ping packets belong to VPN instance M.

The -vpn-instance M option ensures the ping is sent within VPN instance M, allowing verification of MPLS L3VPN routing.

✅ C. During the ping operation, the quantity of ICMP Request packets is Y.

The -cY parameter sets the number of ICMP Echo Requests to be sent, making Y the total count.

✅ D. The size of each ICMP Request packet for the ping operation is Z bytes.

The -sZ parameter defines packet size, helping to test MTU (Maximum Transmission Unit) issues.

Real-World Application:

Verifying MPLS VPN connectivity: Ensure customer networks are reachable within separate VRFs.

Testing MTU & fragmentation: Using -sZ, operators can check if packet fragmentation occurs.

Debugging asymmetric routing issues: By forcing -aX, engineers can trace return paths.

✅ Reference: Huawei HCIE-Datacom Official Guide – MPLS VPN Troubleshooting & Ping Options

To determine R3’s role (Level-1, Level-2, or Level-1-2) based on the provided output of the display ipv6 routing-table protocol isis command on R3, we need to analyze the IS-IS routing information and understand IS-IS hierarchy and behavior, particularly in the context of IPv6 routing. Let’s break it down step by step:

Understanding the IS-IS Levels and Hierarchy:

IS-IS (Intermediate System to Intermediate System) is a link-state routing protocol that supports a two-level hierarchy:

Level-1: Routers within the same area, responsible for intra-area routing. Level-1 routers only maintain routing information for their area and rely on Level-1-2 routers to reach other areas.

Level-2: Routers that form the backbone, connecting different areas for inter-area routing. Level-2 routers maintain routing information across areas.

Level-1-2: Routers that operate both at Level-1 (within their area) and Level-2 (to connect to other areas). These routers act as boundary routers between Level-1 areas and the Level-2 backbone.

A router’s role (Level-1, Level-2, or Level-1-2) determines which types of adjacencies it can form and what routing information it advertises or receives.

Analyzing the Output:

The output shows R3’s IPv6 routing table with routes learned via IS-IS, specifically:

Destination: 2082:EDFC:DDCC::B824:0/127, Protocol: ISIS-L1

This route is learned via IS-IS Level-1 (ISIS-L1), indicating that R3 has a Level-1 adjacency and is receiving or advertising routes within its area.

The next hop (FE80::2E0:FCFF:FE45:6A3E) and interface (GigabitEthernet0/0/0) suggest this route is intra-area.

Destination: 2082:EDFC:DDCC::B891:0/127, Protocol: ISIS-L2

This route is learned via IS-IS Level-2 (ISIS-L2), indicating that R3 has a Level-2 adjacency and is receiving or advertising routes for inter-area or backbone routing.

The next hop (FE80::2E0:FCFF:FE50:406F) and interface (GigabitEthernet0/0/1) suggest this route is for a different area or the backbone.

Both Level-1 and Level-2 routes are present in R3’s routing table, which provides critical insight into R3’s role.

Determining R3’s Role:

Level-1 Routers:

Level-1 routers only participate in Level-1 adjacencies and maintain routing information for their area. They do not have Level-2 routes or adjacencies unless connected to a Level-1-2 router. Since R3 has a Level-2 route (ISIS-L2), it cannot be exclusively a Level-1 router.

Level-2 Routers:

Level-2 routers focus on inter-area routing and typically do not maintain Level-1 routes unless they are also configured as Level-1-2. Since R3 has a Level-1 route (ISIS-L1), it cannot be exclusively a Level-2 router.

Level-1-2 Routers:

Level-1-2 routers operate both at Level-1 (for intra-area routing) and Level-2 (for inter-area routing). They can form adjacencies with both Level-1 and Level-2 neighbors and maintain both types of routes. The presence of both ISIS-L1 and ISIS-L2 routes in R3’s routing table indicates that R3 is participating in both Level-1 and Level-2 adjacencies, making it a Level-1-2 router.

Evaluating Each Option:

A. R3 must be a Level-2 device.

This is incorrect because R3 has ISIS-L1 routes, indicating it is also participating in Level-1 adjacencies, which Level-2-only devices do not do. Level-2 devices focus solely on inter-area routing and do not maintain Level-1 routes.

B. The device role of R3 cannot be determined.

This is incorrect because the presence of both ISIS-L1 and ISIS-L2 routes in the routing table clearly indicates R3’s role. The combination of Level-1 and Level-2 routes confirms R3 is a Level-1-2 router.

C. R3 must be a Level-1-2 device.

This is correct. The routing table shows both ISIS-L1 (Level-1) and ISIS-L2 (Level-2) routes, meaning R3 is operating as both a Level-1 and Level-2 router, which defines a Level-1-2 device.

D. R3 must be a Level-1 device.

This is incorrect because R3 has ISIS-L2 routes, indicating it is also participating in Level-2 adjacencies, which Level-1-only devices do not do. Level-1 devices only maintain intra-area routes and rely on Level-1-2 routers for inter-area reachability.

Additional Considerations:

The Flags: D in the output typically indicates a directly connected route or a route downloaded to the forwarding table, but it does not affect the determination of R3’s IS-IS level.

The preference (15) and cost (20) are standard for IS-IS routes and do not impact the level determination.

In Huawei’s IS-IS implementation, routers can be configured explicitly as Level-1, Level-2, or Level-1-2 using commands like isis level-1-2 under the IS-IS process. The presence of both Level-1 and Level-2 routes confirms R3’s configuration as Level-1-2.

Huawei HCIE-Datacom Context:

According to Huawei HCIE-Datacom documentation, IS-IS routers can operate at different levels, and the routing table’s protocol type (ISIS-L1 or ISIS-L2) indicates the level of adjacency. A router with both Level-1 and Level-2 routes is necessarily a Level-1-2 device, as it participates in both intra-area and inter-area routing.

The display ipv6 routing-table protocol isis command on Huawei devices shows routes learned via IS-IS, and the protocol type (L1 or L2) directly reflects the router’s role in the IS-IS hierarchy.

Conclusion:

Based on the presence of both ISIS-L1 and ISIS-L2 routes in R3’s IPv6 routing table, R3 must be a Level-1-2 device, as it is participating in both Level-1 (intra-area) and Level-2 (inter-area) adjacencies. Therefore, the correct answer is C.

References to Huawei HCIE-Datacom Documents:

Huawei HCIE-Datacom V1.0 Training Material, Chapter on IS-IS Configuration and Hierarchy.

Huawei NE Series Router Configuration Guide, IS-IS Section (Level-1, Level-2, and Level-1-2 Operations).

Huawei Technical Whitepaper on IS-IS Protocol, discussing IPv6 Routing and Level Determination.

In MPLS VPN, packets are forwarded using two labels:

Outer label (Transport Label) – Used by the MPLS backbone for forwarding.

Inner label (VPN Label) – Used by the egress PE to identify the correct VPN instance.

Explanation of Correct Options:

✅ A. The egress PE sends the data packet to the correct VPN based on the inner label.

The inner label is assigned by the egress PE and determines the final destination VPN instance.

✅ B. The penultimate hop removes the outer label before forwarding the data packet to a peer egress PE.

Penultimate Hop Popping (PHP) occurs when the second-to-last router (P router) removes the outer MPLS label before forwarding to the egress PE.

This reduces the processing overhead on the egress PE.

✅ D. The penultimate-hop device receives a packet with an outer label.

The outer label is used to forward the packet across the MPLS backbone.

Before reaching the egress PE, the penultimate router still has the outer label and processes it.

Incorrect Option:

❌ C. The IP data packet received by the egress LSR is without labels.

This is incorrect because the inner label (VPN label) is still present when the packet reaches the egress PE.

Only the outer label is removed by PHP, not the inner VPN label.

Reference from Huawei HCIE-Datacom Documentation:

Huawei MPLS VPN Configuration Guide – Label Processing

HCIE-Datacom MPLS Traffic Engineering and PHP Mechanism

Huawei iMaster NCE-Campus MPLS VPN Implementation Guide

NAFTIR (Network Address Flow Traffic Incoming Rate) policing is a traffic control mechanism that can only be applied to inbound traffic.

Purpose:

Monitors and limits the traffic entering a network device.

Prevents upstream devices from overloading the network with excessive data.

Key Fact: Outbound policing requires different mechanisms like QoS shaping or traffic scheduling.

✅ Reference: Huawei HCIE-Datacom Study Guide - Traffic Policing and Shaping

Understanding VXLAN and ARP Suppression in BGP EVPN

VXLAN (Virtual Extensible LAN) is used to extend Layer 2 networks over Layer 3 infrastructure.

VXLAN uses VTEPs (VXLAN Tunnel Endpoints) to encapsulate and forward Layer 2 traffic.

BGP EVPN (Ethernet VPN) is used for MAC/IP address learning and distribution across VXLAN networks.

How ARP Request Forwarding Works in This Scenario?

1️⃣ ARP Broadcast Suppression Enabled (VXLAN Optimized Forwarding)

Since ARP broadcast suppression is enabled on VTEP1, the ARP request is not flooded.

Instead, VTEP1 checks its EVPN learned database to find PC2’s MAC address (MAC C).

2️⃣ VTEP1 Encapsulates the ARP Request

VTEP1 encapsulates the ARP request in a VXLAN packet and sends it to VTEP2.

The original ARP frame inside the VXLAN tunnel still has:

Source MAC: MAC A (PC1's MAC)

Destination MAC: MAC C (PC2's MAC, learned via EVPN)

3️⃣ VXLAN Outer Headers

The outer VXLAN header uses:

Source IP: 1.1.1.1 (VTEP1)

Destination IP: 2.2.2.2 (VTEP2)

VNI (VXLAN Network Identifier): 200 (BD 20)

4️⃣ VTEP2 Receives and Forwards the ARP Request

VTEP2 decapsulates the VXLAN packet and forwards the original ARP request to PC2 (MAC C).

This ensures that only the intended receiver (PC2) gets the ARP request, preventing unnecessary broadcast flooding.

Why the Answer is MAC C?

✅ B. MAC C is Correct

The destination MAC of the inner data frame is PC2’s MAC (MAC C).

This is because VTEP1 forwards the ARP request directly to VTEP2, which then forwards it to PC2.

Why Other Answers Are Incorrect?

❌ A. MAC B (Incorrect)

MAC B is VTEP1’s MAC address, which is used in the outer VXLAN header, not in the inner Ethernet frame.

❌ C. MAC A (Incorrect)

MAC A is the source MAC of the ARP request (PC1), not the destination.

❌ D. MAC D (Incorrect)

MAC D is not mentioned in the topology, so it is irrelevant.

???? Reference: Huawei HCIE Datacom – VXLAN BGP EVPN and ARP Suppression

Comprehensive and Detailed Explanation:

The reset isis all command resets the entire IS-IS process, including:✔ Neighbor adjacencies✔ LSDB (Link-State Database)✔ All IS-IS-related statistics

Key Points:

This command resets IS-IS completely, causing temporary route convergence delays.

All IS-IS statistics are cleared because the process restarts from scratch.

Since the question states that IS-IS statistics are not cleared, which is incorrect, the correct answer is FALSE.

???? Reference: Huawei HCIE Datacom – IS-IS Troubleshooting and Reset Commands

SRv6 Instruction Naming Conventions

SRv6 (Segment Routing over IPv6) uses segment identifiers (SIDs) with specific functions, indicated by instruction keywords:

✅ A. T: Searches a specified routing table to forward packets.

T (Table Lookup) → Performs a lookup in a specified routing table and forwards packets accordingly.

❌ B. M: Searches a Layer 2 forwarding table for unicast forwarding.

Incorrect! SRv6 does not use M for Layer 2 unicast forwarding.

✅ C. V: Searches a VPN instance routing table to forward packets.

V (VPN Routing Table Lookup) → Performs a lookup in a VPN instance (VRF) table for forwarding.

✅ D. X: Forwards packets through one or a group of specified Layer 3 interfaces.

X (Cross-connect forwarding) → Forwards packets via a specified Layer 3 interface or group of interfaces.

Reference from Huawei HCIE-Datacom Documentation:

Huawei SRv6 Configuration Guide – SRv6 SID Naming and Instruction Set

HCIE-Datacom Study Material – Segment Routing over IPv6 (SRv6) Functionality

Huawei iMaster NCE-Campus provides open APIs for seamless integration with third-party applications and services. Each API serves a specific purpose in managing network security, operations, analytics, and user interactions.

1. Authentication and authorization → Third-party authentication API

This API is used to integrate third-party authentication systems, such as:

LDAP (Lightweight Directory Access Protocol)

RADIUS (Remote Authentication Dial-In User Service)

OAuth/OpenID authentication

It ensures secure user identity verification, access control, and single sign-on (SSO) in CloudCampus networks.

2. Network O&M → Infrastructure API

The Infrastructure API provides tools for network monitoring, diagnostics, and automated management.

It is used for:

Device status monitoring

Network topology visualization

Fault detection and real-time alerts

Performance optimization

3. LBS (Location-Based Services) → LBS API

The LBS API enables applications to access location data collected by the network.

It is used for:

Tracking users or assets within a campus network

Heatmap generation and movement analytics

Geo-fencing and location-based policies

4. Crowd profiling → VAS API

VAS (Value-Added Services) API is designed for advanced analytics and business intelligence.

It supports:

User behavior analytics

Demographic profiling

Marketing strategies based on network usage patterns

Reference from Huawei HCIE-Datacom Documentation:

HCIE-Datacom Training Guide – CloudCampus Solution

Huawei iMaster NCE-Campus API Documentation

Huawei CloudCampus Solution Whitepaper – Open API and Use Cases

Understanding SRLB (Segment Routing Local Block)

???? What is SRLB?

SRLB (Segment Routing Local Block) is a range of local MPLS labels used by Segment Routing (SR-MPLS).

These labels are only relevant to the local router and are not advertised to other routers.

???? Key SR-MPLS Label Blocks:✅ SRGB (Segment Routing Global Block) – Globally significant labels shared among routers.✅ SRLB (Segment Routing Local Block) – Locally significant labels, not shared.

Why is the Answer TRUE?

✅ SRLB labels are only locally defined and are NOT distributed via IGP (OSPF or IS-IS).✅ They are used for local forwarding decisions within an SR-enabled router.✅ Only SRGB labels are advertised to ensure consistent global label assignment.

Real-World Application:

Traffic Engineering (TE): Uses SRLB for custom local path optimizations.

Segment Routing Networks: Ensures scalable MPLS forwarding without requiring full LDP signaling.

✅ Reference: Huawei HCIE-Datacom Guide – Segment Routing Label Blocks (SRGB & SRLB)

Understanding 802.1X Authentication in Enterprise Networks

???? What is 802.1X?

802.1X is a network access control (NAC) protocol that enforces authentication before allowing a device to connect to a LAN.

It uses EAP (Extensible Authentication Protocol) over RADIUS for user verification.

Typically deployed in corporate and campus networks for secure wired and wireless access.

???? How Does 802.1X Work?1️⃣ Client (Supplicant) → Requests network access.2️⃣ Switch (Authenticator) → Forwards request to RADIUS server.3️⃣ RADIUS Server → Verifies credentials & grants access.

Mandatory Steps to Enable 802.1X on SW3

✅ A. Configure an AAA Scheme

Defines authentication, authorization, and accounting (AAA) methods.

Links 802.1X authentication to the RADIUS server.

✅ B. Configure an Authentication Profile

Specifies how authentication is handled on the switch.

Associates 802.1X authentication with an AAA scheme.

✅ C. Configure an Authentication Domain

Groups authentication policies for different user types.

Maps AAA scheme to user login requests.

✅ D. Configure an 802.1X Access Profile

Applies 802.1X authentication to specific switch ports (GE0/0/2 & GE0/0/3).

Ensures that only authenticated users can pass traffic.

Why Are All Four Steps Necessary?

✅ Each step plays a critical role in enabling 802.1X authentication and linking it to the RADIUS server.✅ Without any one of these configurations, the 802.1X authentication process would fail.

Real-World Application:

Enterprise Wired Security: Ensures that only authenticated devices access corporate networks.

University Campuses & Public Wi-Fi: Prevents unauthorized access to secure LAN environments.

✅ Reference: Huawei HCIE-Datacom Guide – 802.1X Authentication & RADIUS Server Configuration

Understanding the Telemetry Output:

Dest-addr: 192.168.56.1 → The destination IP address is 192.168.56.1. ✅

Dest-name: Dest1 → The destination group name is Dest1. ✅

Protocol: gRPC → Data push uses the gRPC protocol. ✅

Vpn-name: - (empty) → No VPN encapsulation is used. ❌

Incorrect Answer Explanation:

❌ C. "VPN encapsulation is used for data push" → Incorrect!

The Vpn-name field is empty, indicating that VPN encapsulation is NOT enabled for telemetry data transport.

Reference from Huawei HCIE-Datacom Documentation:

Huawei Telemetry Configuration Guide – Destination and Data Push Methods

HCIE-Datacom Study Material – gRPC and Telemetry Data Streaming

Comprehensive and Detailed Explanation:

The IS-IS peer output shows:

IPv4 Peer Address: 10.1.34.1

IPv6 Peer Address: FE80::2E0:FCFF:FE98:2576

MT IDs (Multi-Topology) Supported: 0 (IPv4), 2 (IPv6)

Since both IPv4 and IPv6 peer addresses are listed, it confirms that both IPv4 and IPv6 IS-IS neighbor relationships are established between R4 and ee8c.a0c2.baf3.

???? Reference: Huawei HCIE Datacom – IS-IS Multi-Topology Support

Huawei iMaster NCE-Campus as an Authentication Relay Agent

Huawei iMaster NCE-Campus can act as a relay agent for authentication services, forwarding authentication requests between users and authentication servers (e.g., RADIUS, LDAP).

✅ B. User Authentication

Validates user credentials before granting network access.

Supports 802.1X, Portal, MAC, and RADIUS authentication.

✅ C. User Analysis

Analyzes user behavior and access patterns to optimize security and network policies.

✅ D. Marketing

Provides customized authentication portals with advertisements and promotional messages.

Incorrect Answer:

❌ A. User Accounting – Accounting is handled by the authentication server (e.g., RADIUS), not the relay agent.

Reference from Huawei HCIE-Datacom Documentation:

Huawei iMaster NCE-Campus Authentication Guide – Relay Agent Functions

HCIE-Datacom Study Material – User Authentication and Analysis in CloudCampus

Understanding IRB (Integrated Routing and Bridging) Forwarding in VXLAN

VXLAN (Virtual Extensible LAN) supports Layer 2 and Layer 3 forwarding between Virtual Network Identifiers (VNIs).

IRB (Integrated Routing and Bridging) enables inter-subnet communication within a VXLAN fabric.

There are two modes of IRB forwarding:

Symmetric IRB

Asymmetric IRB

Why the Answer is "Symmetric" IRB Forwarding?

✔ Ingress VTEP performs both Layer 2 and Layer 3 lookups:

Symmetric IRB requires both ingress and egress VTEPs to perform Layer 3 lookups.

The ingress VTEP (source gateway) performs a Layer 2 MAC lookup, then a Layer 3 lookup to find the destination VTEP.

The egress VTEP (destination gateway) performs another Layer 3 lookup before forwarding the packet to the destination.

✔ Asymmetric IRB does not perform two lookups at the ingress VTEP:

In Asymmetric IRB, the ingress VTEP performs both Layer 2 and Layer 3 forwarding and sends a Layer 2 packet to the egress VTEP.

The egress VTEP only does a Layer 2 lookup, not a Layer 3 lookup.

Since the question states that both L2 and L3 lookups occur at the ingress VTEP, asymmetric IRB is incorrect.

✔ Why Symmetric IRB is More Common?

Scalability: Supports any-to-any communication across VXLAN networks.

More Efficient Routing: Uses Layer 3 VXLAN encapsulation, ensuring efficient routing between VNIs.

???? Reference: Huawei HCIE Datacom – VXLAN Symmetric and Asymmetric IRB Forwarding

Understanding Telemetry Encoding Formats

???? What is Telemetry?

Telemetry is a real-time network monitoring method that provides high-frequency data collection.

Used in AI-driven networks for predictive analytics and automation.

???? Common Telemetry Encoding Formats:

✅ GPB (Google Protocol Buffers)

Highly efficient binary format that reduces message size and CPU overhead.

Commonly used for high-speed, real-time analytics.

✅ JSON (JavaScript Object Notation)

Human-readable format, widely used in RESTful APIs.

Less efficient than GPB in high-speed telemetry but easier to debug.

???? Why is the Answer FALSE?❌ GPB is not mandatory; JSON can also be used in telemetry.✅ Huawei supports both GPB and JSON telemetry encoding formats.

Real-World Application:

Cloud Networking: Uses GPB for fast data collection and JSON for API-based telemetry visualization.

AI-Driven Networks: High-speed AI analytics leverage GPB encoding for efficiency.

✅ Reference: Huawei HCIE-Datacom Guide – Telemetry Encoding Formats and Data Collection

Understanding Prefix Lists

IP Prefix-Lists are used for filtering BGP routes and controlling route advertisement & redistribution.

The command ip ip-prefix TEST permit 10.0.0.0 24 less-equal 30 means:

Matches prefix 10.0.0.0/24 exactly.

Matches any subnet of 10.0.0.0/24 with a prefix length between 24 and 30.

Analysis of Routes:

✅ 10.0.0.0/24 → Matches exactly.

✅ 10.0.0.1/30 → Falls within 10.0.0.0/24 & length ≤30.

❌ 10.0.1.0/24 → Not within 10.0.0.0/24 range.

❌ 10.0.2.0/24 → Not within 10.0.0.0/24 range.

Real-World Use Case:

BGP route filtering: Only allows 10.0.0.0/24 and its subnets (up to /30).

Prevents unintended route propagation in large-scale networks.

✅ Reference: Huawei HCIE-Datacom Guide – BGP Prefix-Lists

Next Steps

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Excellent! I will continue with the next set of questions, ensuring that the explanations are even more in-depth, covering:

✅ Concepts & technical background✅ Detailed breakdown of key terms✅ Real-world applications & scenarios✅ Huawei HCIE-Datacom official references

This will make sure you have complete clarity and practical understanding of each topic. Let’s move forward ????

BGP EVPN in VXLAN Tunneling

✅ A. MP_REACH_NLRI is used to carry routing information.

MP_REACH_NLRI (Multiprotocol Reachable Network Layer Reachability Information) is used in BGP updates to carry VXLAN reachability information.

✅ B. Several BGP EVPN routes are defined through BGP extension.

BGP EVPN introduces multiple route types, such as Type 2 (MAC/IP Advertisement), Type 3 (Inclusive Multicast), and Type 5 (IP Prefix Advertisement).

✅ D. MP_REACH_NLRI is used to carry the RT.

RT (Route Target) defines route import/export policies in VPN environments.

MP_REACH_NLRI carries the RT attribute in BGP EVPN updates.

❌ Incorrect Answer:❌ C. MP_REACH_NLRI is used to carry the RD.

Wrong! The Route Distinguisher (RD) is carried inside BGP attributes, but not in MP_REACH_NLRI.

Reference from Huawei HCIE-Datacom Documentation:

Huawei VXLAN BGP EVPN Configuration Guide – BGP EVPN Route Types

HCIE-Datacom Training Material – VXLAN Dynamic Tunnel Establishment

Comprehensive and Detailed Explanation:

R2 is an Area Border Router (ABR), meaning it connects multiple OSPF areas (Area 0 and Area 1).

ABRs generate Router-LSAs for each area they belong to.

Since R2 is part of both Area 0 and Area 1, it must generate Router-LSAs (Type 1) for both areas.

R2 does not forward Router-LSAs between areas; instead, it generates Summary LSAs (Type 3) to exchange routing information between areas.

Thus, the correct answer is D.

???? Reference: Huawei HCIE Datacom – OSPF LSA Types and ABR Behavior

Understanding BFD (Bidirectional Forwarding Detection)

BFD is a high-speed fault detection protocol used to monitor link failures in milliseconds.

It operates at Layer 2 (Data Link Layer) and Layer 3 (Network Layer) to provide fast convergence.

Why Can BFD Detect Failures in Milliseconds?

Uses lightweight control packets that are exchanged between routers.

Works with OSPF, IS-IS, BGP, and MPLS to trigger fast convergence.

Detection time = (Transmit Interval) × (Detect Multiplier)

Example: If the interval is 3ms and the multiplier is 3, failure detection takes 9ms.

Why is the Answer TRUE?

✅ BFD achieves millisecond-level detection by sending rapid probe packets.✅ Used in high-availability networks where link failures must be detected in real-time.

Real-World Application

Service Provider Networks: BFD improves network resilience by detecting link failures faster than traditional routing timers.

Enterprise WANs: Used in SD-WANs to switch paths dynamically.

MPLS Fast Reroute (FRR): Works with MPLS Traffic Engineering for near-instantaneous failover.

✅ Reference: Huawei HCIE-Datacom Guide – BFD for Fast Link Failure Detection

Understanding Jinja2 Templates in Huawei SSP Packages

???? What is Jinja2?

Jinja2 is a templating engine used in Huawei SSP (Smart Script Package) automation.

It allows dynamic configuration generation based on variables and logic.

???? Jinja2 Syntax Basics:✅ {% ... %} → Used for control structures like loops and conditions.✅ {{ ... }} → Used for variable placeholders.

Example of a Jinja2 Template Using {% ... %} for a Loop:

jinja2

CopyEdit

{% for interface in interfaces %}

interface {{ interface.name }}

description {{ interface.description }}

{% endfor %}

???? This template dynamically generates interface configurations based on a list of interfaces.

Why is the Answer TRUE?

✅ {% ... %} is used for control structures in Jinja2 templates (e.g., loops, if-else statements).✅ Jinja2 templates are widely used in SSP for Huawei network automation.

Real-World Application:

Automated Network Configuration: Uses Jinja2 in Huawei SSP automation scripts.

Data Center & SDN Automation: Dynamically generates VXLAN, BGP, and OSPF configurations.

✅ Reference: Huawei HCIE-Datacom Guide – Jinja2 Templates in SSP Packages

Comprehensive and Detailed Explanation:

Ethernet VPN (EVPN) is an advanced L2VPN technology that enhances MAC learning and forwarding in data center and enterprise networks. Different EVPN route types are used for various functions:

Ethernet A-D (Auto-Discovery) Route: Used for auto-discovery of PE devices and does carry labels.

MAC/IP Advertisement Route: Distributes MAC-to-IP mappings and carries labels for forwarding decisions.

Ethernet Segment Route: Does not carry MPLS labels as it is used to signal multi-homing and redundancy information.

Inclusive Multicast Route: Used for multicast forwarding and carries labels for tunnel identification.

Since Ethernet Segment Route is used only for multi-homing signaling and does not carry MPLS labels, the correct answer is C.

???? Reference: Huawei HCIE Datacom Study Guide - EVPN Route Types

VXLAN Inter-Subnet Routing with Symmetric IRB

VXLAN supports inter-subnet routing using Integrated Routing and Bridging (IRB). In symmetric IRB, both ingress and egress VTEPs perform Layer 3 forwarding to ensure efficient packet forwarding across subnets.

✅ A. Both the ingress VTEP and egress VTEP forward packets based on the Layer 3 forwarding table.

In symmetric IRB, both ingress and egress VTEPs perform Layer 3 lookup and forwarding.

The ingress routes packets before encapsulating them in VXLAN, and the egress performs another Layer 3 lookup to determine final delivery.

✅ D. When VTEPs forward inter-subnet user communication packets, the VNI carried in the VXLAN header is the L3VNI.

L3VNI (Layer 3 VXLAN Network Identifier) is used for inter-subnet routing between VXLAN segments.

Understanding SR-MPLS TE (Segment Routing MPLS Traffic Engineering)

???? What is SR-MPLS TE?

Segment Routing (SR) replaces traditional MPLS LDP/RSVP-TE signaling.

Uses SR-TE policies to define network paths without requiring per-flow state on intermediate routers.

???? How is the SR-MPLS TE Path Calculated?✅ By the SDN Controller (Centralized Path Computation)

The controller (e.g., Huawei iMaster NCE) calculates the optimal SR path based on:

Bandwidth requirements

Latency constraints

Traffic policies

The controller then delivers the SR policy to the ingress router.

✅ By the Ingress Router (Distributed Path Computation)

The ingress router computes the SR path dynamically based on local constraints.

This method is useful when no centralized controller is available.

Why is the Answer TRUE?

✅ Both centralized (controller-based) and distributed (ingress router-based) path computation are supported in SR-MPLS TE.

Real-World Application:

5G and Cloud WANs: Centralized path optimization reduces congestion dynamically.

Enterprise Networks: Local path computation ensures fast rerouting in case of failures.

✅ Reference: Huawei HCIE-Datacom Guide – SR-MPLS TE and Path Computation Methods

Comprehensive and Detailed Explanation:

✔ BIER vs. PIM Multicast Routing:

BIER (Bit Index Explicit Replication) eliminates the need for multicast distribution trees (MDTs) by encoding receiver information into the packet header.

PIM (Protocol Independent Multicast) requires MDTs to manage multicast forwarding paths.

✔ Correct Statements:✅ (A) BIER uses a Bitstring field in packet headers for forwarding.✅ (B) PIM builds MDTs to define multicast paths.✅ (C) BIER does NOT require MDTs, making it more scalable.

❌ (D) Incorrect → BIER does not require hop-by-hop join messages.

???? Reference: Huawei HCIE Datacom – BIER and PIM Comparison

Understanding VGMP (Virtual Gateway Management Protocol)

???? What is VGMP?

VGMP (Virtual Gateway Management Protocol) is used in Huawei firewalls to manage hot standby (HRP - Hot Standby Routing Protocol).

Ensures that the active and standby firewalls synchronize their states for high availability.

???? How Does VGMP Work?

The Active and Standby firewalls exchange VGMP packets to maintain state synchronization.

These packets are encapsulated within UDP for transport.

The default UDP port for VGMP is 512.

Why is the Answer 512?

✅ Huawei firewalls use UDP port 512 by default for VGMP communication.✅ This ensures that VGMP heartbeats and synchronization messages are correctly processed.

Real-World Application:

Enterprise Firewalls: VGMP ensures failover between active and standby firewalls.

Carrier-Grade Firewalls: Uses VGMP with HRP to achieve zero-downtime firewall redundancy.

✅ Reference: Huawei HCIE-Datacom Guide – VGMP and HRP High Availability Mechanisms

Comprehensive and Detailed Explanation:

The IS-IS metric (cost) determines the shortest path selection.

The isis cost command is used to manually set the cost of an IS-IS interface.

Command Breakdown:

✔ isis cost <value> – Adjusts the cost of an interface in the IS-IS routing protocol.✔ Lower cost means higher priority in route selection.

Why Are Other Options Incorrect?

❌ isis circuit-type – Sets the circuit type (L1, L2, L1/L2) but does not change cost.❌ isis timer hello – Adjusts hello interval timing, not path cost.❌ isis circuit-level – Defines interface level (L1, L2) but does not impact cost.

Thus, the correct answer is C.

???? Reference: Huawei HCIE Datacom – IS-IS Path Cost Adjustment

Telemetry Data Collection in Huawei Devices

Telemetry allows real-time streaming of network performance data based on predefined sampling paths. Supported sampling paths include:

✅ A. Interface statistics

Monitors real-time traffic usage, errors, and packet loss on interfaces.

✅ C. CPU information

Tracks CPU utilization and performance metrics.

✅ D. Memory information

Monitors RAM usage and system memory consumption.

Incorrect Answer:

❌ B. Information about the optical module on an interface

Telemetry does not natively support direct optical module monitoring; instead, SNMP or CLI commands like display transceiver are used.

Reference from Huawei HCIE-Datacom Documentation:

Huawei Telemetry Configuration Guide – Supported Sampling Paths

HCIE-Datacom Study Material – Network Performance Monitoring with Telemetry

Understanding Northbound APIs in Huawei iMaster NCE-WAN

???? What is a Northbound API?

Northbound APIs allow external applications (e.g., SDN controllers, orchestration tools) to communicate with Huawei iMaster NCE-WAN.

Used for automation, monitoring, and network configuration.

Analysis of Each API Type:

✅ A. NETCONF (Network Configuration Protocol)

Correct: NETCONF is an IETF-standardized protocol for network configuration management.

Huawei iMaster NCE-WAN supports NETCONF for dynamic configuration of SD-WAN devices.

✅ B. RESTful API (Representational State Transfer API)

Correct: RESTful APIs provide HTTP-based programmatic access to SD-WAN functions.

Used for cloud-native SD-WAN automation and integration.

❌ C. CLI (Command Line Interface) (Incorrect Choice)

CLI is not a northbound API; it is a manual command interface used directly on devices.

❌ D. SNMP (Simple Network Management Protocol) (Incorrect Choice)

SNMP is used for network monitoring, not for northbound API communications.

Real-World Application:

Cloud-based SD-WAN Automation: Uses RESTful API for seamless integration with third-party cloud orchestration tools.

Zero-Touch Provisioning (ZTP): Uses NETCONF API to push configurations to branch SD-WAN routers.

✅ Reference: Huawei HCIE-Datacom Guide – SD-WAN API Integration and Automation

VRRP (Virtual Router Redundancy Protocol) and Flapping

VRRP ensures gateway redundancy by allowing multiple routers to work together as a virtual router. Flapping occurs when the master and backup routers frequently switch roles.

Causes of VRRP Flapping:

✅ A. Too small interval between Advertisement packet transmissions – Can cause flapping

If the Advertisement interval is too short, frequent VRRP state changes can occur.

✅ C. Packet loss on an interface of the backup device – Can cause flapping

If the backup router loses VRRP packets, it might assume the master is down and initiate an election.

✅ D. Flapping on the link transmitting VRRP Advertisement packets – Can cause flapping

If the link used for VRRP experiences instability, packets may be lost, triggering VRRP role changes.

Incorrect Answer Explanation:

❌ B. Inconsistent preemption delay settings – Does NOT cause VRRP flapping

Preemption delay only affects when a router takes over as master after recovering from a failure.

It does not directly cause flapping because the role change happens only after a delay, preventing frequent transitions.

Reference from Huawei HCIE-Datacom Documentation:

Huawei VRRP Configuration Guide – Preventing VRRP Flapping

HCIE-Datacom Study Material – VRRP Timers and Stability

Comprehensive and Detailed Explanation:

The Huawei Registration Query Center allows devices to register and go online automatically in a cloud-managed environment.

✔ Supported Devices:

Switches ✅

Access Routers (AR) ✅

Access Points (APs) ✅

Firewalls ✅

✔ How It Works:

Devices obtain their registration information via DHCP Option 148 or pre-configured credentials.

The devices then connect to the registration query center to retrieve configuration and authentication details.

Once authenticated, they go online and become manageable via iMaster NCE-Campus.

???? Reference: Huawei HCIE Datacom – CloudCampus Device Registration

Comprehensive and Detailed Explanation:

The OSPF error output shows:✔ Hello timer mismatch (1 error) → Hello intervals must match for adjacency formation (A) ✅✔ No Netmask mismatch errors → Subnet masks are consistent, so option C is incorrect ❌✔ No Extern option mismatch → No evidence of area type inconsistency (option D) ❌✔ If area IDs were mismatched, adjacency would not form (option B is correct) ✅

Thus, the correct answers are A and B.

???? Reference: Huawei HCIE Datacom – OSPF Troubleshooting

Comprehensive and Detailed Explanation:

✔ SRv6 (Segment Routing over IPv6) Flavors provide additional processing behaviors for SRv6 End instructions.

✔ PSP (Penultimate Segment Popping) Flavor:

PSP enables the penultimate node to remove the SRH (Segment Routing Header) before forwarding the packet to the last segment.

This reduces the processing overhead on the final segment node.

✔ Correct End Instructions for PSP:✅ (A) End.X → Cross-connect behavior between segments.✅ (C) End.T → Transport encapsulation in SRv6.✅ (D) End → Basic SRv6 endpoint behavior.

❌ (B) End.BM is incorrect → This is used for Binding Segment (BSID) behavior and does not support PSP.

???? Reference: Huawei HCIE Datacom – SRv6 Flavors and End Instructions

Comprehensive and Detailed Explanation:

VXLAN Symmetric IRB (Integrated Routing and Bridging) Forwarding is used for inter-subnet communication between different VXLAN networks.

✔ L3VNI is used for inter-subnet traffic → (A) Correct✔ Both ingress and egress VTEPs perform Layer 3 forwarding → (B) Correct

Why Are the Other Options Incorrect?

❌ C (Incorrect): The ingress VTEP uses both L2 and L3 forwarding (not just L2).❌ D (Incorrect): The egress VTEP also performs L3 forwarding before sending packets to the destination VTEP.

???? Reference: Huawei HCIE Datacom – VXLAN Symmetric IRB Forwarding

SSH Public Key Authentication

In public key authentication mode, the SSH client must generate a key pair (public and private keys) before connecting to an SSH server.

✅ C. ssh-keygen -t dsa (Correct Answer)

DSA (Digital Signature Algorithm) key generation for SSH authentication.

Generates a private key (id_dsa) and a public key (id_dsa.pub).

Virtual Networks in Huawei CloudCampus Solution:

Virtual networks (VNs) are segmented based on services (e.g., IoT, Guest Wi-Fi, Enterprise Wi-Fi).

Each VN has its own routing and forwarding instance (VRF).

Isolation Between Virtual Networks:

By default, different virtual networks are isolated.

If inter-VN communication is required, it must be manually configured using policy-based routing (PBR), inter-VRF routing, or firewall policies.

Reference from Huawei HCIE-Datacom Documentation:

Huawei CloudCampus Solution Guide – Virtual Networks and Segmentation

HCIE-Datacom Training Material – Policy-Based Inter-VN Communication

Comprehensive and Detailed Explanation:

Inter-AS MPLS L3VPN Option B requires ASBRs to exchange VPNv4 routes using eBGP with label information.

Analysis of Inter-AS VPN Solutions:

A screenshot of a computer AI-generated content may be incorrect.

Option B uses eBGP to exchange labeled VPNv4 routes between ASBRs but does not require MPLS between ASBRs.

Option A does not exchange VPNv4 routes over ASBRs (uses IP routing instead).

Option C uses MP-BGP and requires full MPLS between ASBRs.

Since Option B requires ASBRs to exchange VPNv4 routes, the correct answer is B.

???? Reference: Huawei HCIE Datacom – MPLS Inter-AS VPNs